CN110603814A

CN110603814A - System, method and device for communication in a noisy environment

Info

Publication number: CN110603814A
Application number: CN201780084898.7A
Authority: CN
Inventors: 凯万·詹姆斯·汤普森·安德森; 唐纳德·布鲁斯·普莱韦斯; 柳家俊; 大卫·罗伯特·格林; 林西·亚历山德拉·玛丽·托马森
Original assignee: Innville Medical Co
Current assignee: Innville Medical Co
Priority date: 2016-11-28
Filing date: 2017-11-28
Publication date: 2019-12-20
Anticipated expiration: 2037-11-28
Also published as: BR112019010843A2; EP3545689A4; AU2017365735A1; JP7252629B2; US20200374615A1; EP3545689A1; WO2018094538A1; JP2019537401A; CN110603814B; US11601742B2

Abstract

The present disclosure provides communication systems and devices for use in noisy environments such as during Magnetic Resonance Imaging (MRI). In some embodiments, a communication headrest is provided that includes a headrest that supports a patient's head, an optional bone conduction microphone, and one or more vibration actuators. The headset is in contact with a noise isolating ear plug worn by the subject such that vibrations generated by the vibration actuator are transmitted through the ear plug via acoustic conduction to enable the patient to hear audio content while the ear plug provides passive noise protection by closing the ear canal. In other embodiments, an active earplug apparatus is provided in which the acoustic energy transducer is contacted and supported by the noise isolating earplug such that when the earplug is inserted into the ear canal, the acoustic energy transducer is in acoustic conductive communication with tissue surrounding the ear canal, thereby facilitating acoustic communication by bone conduction.

Description

System, method and device for communication in a noisy environment

Cross Reference to Related Applications

Priority is given to united states provisional application No. 62/427, 072, filed on 28/11/2016, entitled "system, method AND apparatus for communicating IN a NOISY environment" (SYSTEMS, METHODS AND devices), the entire contents of which are incorporated herein by reference.

Background

The present disclosure relates to systems and methods for facilitating communication in noisy environments. More particularly, aspects of the present disclosure relate to patient communication systems and methods for magnetic resonance imaging.

It is well known that Magnetic Resonance Imaging (MRI) systems generate significant noise during scanning due to acoustic vibrations of the gradient coils. Passive ear protection devices in the form of ear plugs are typically provided to the patient during MRI scanning. Such an earplug is very effective in reducing ambient noise and can achieve greater than 30dB of sound insulation. Communication with the patient in an MRI environment is challenging due to the loud noise and the need to protect the ear. Communication with the scan technician is typically performed through a speaker and microphone located in the bore of the MRI scanner. However, because of the noise generated by the scanner during operation, communication is typically limited to periods of non-operation between image acquisitions.

Several different patient communication systems have been developed to address this problem. For example, some patient communication systems use air tubes with foam ear bud tips, while other patient communication systems use wearable headsets with piezoelectric and other vibration actuators to facilitate communication with the patient.

Wearable headsets can be designed to achieve a significant degree of passive noise isolation from ambient noise. However, in order to provide sufficient noise suppression for use with MRI scanners, the headset needs to surround the ear with a large cavity or "cushion". This may limit the use in a limited space such as a head coil. Air hoses are also often used to help patients with hearing, but generally provide poor passive noise isolation.

Other patient communication systems employ earplugs with an air passage between the ear canal and an actuator supported by the earplugs. Passive noise isolation of such systems may be poor because the ear canal is not closed.

Some patient communication systems employ optical microphones to facilitate communication between the patient and the scanning technician. Such microphones need to be placed close to the mouth of the patient and therefore their use in confined spaces, such as inside certain head coils, is limited.

Other patient communication systems employ bone conduction microphones that can be used to detect speech that has significant immunity to ambient noise and thus can be used in noisy environments. Bone conduction microphones detect bone and tissue vibrations produced by the vocal cords. Commercial examples of vibrating microphones utilize accelerometers, inertial sensors, and piezoelectric elements.

Disclosure of Invention

The present disclosure provides communication systems and devices for use in noisy environments, for example during Magnetic Resonance Imaging (MRI). In some embodiments, a communication headrest is provided that includes a headrest that supports a patient's head, an optional bone conduction microphone, and one or more vibration actuators. The headset is in contact with a noise isolating ear plug worn by the subject such that vibrations generated by the vibration actuator are transmitted through the ear plug via acoustic conduction to enable the patient to hear audio content while the ear plug provides passive noise protection by closing the ear canal. In other embodiments, an active earplug apparatus is provided in which an acoustic energy transducer is in contact with and supported by a noise isolating earplug such that when the earplug is inserted into an ear canal, the acoustic energy transducer is in acoustic conductive communication with tissue surrounding the ear canal, thereby facilitating acoustic communication through bone conduction.

Accordingly, in a first aspect, there is provided an acoustic communication device for use during magnetic resonance imaging, the acoustic communication device comprising:

a headrest positionable within a magnetic resonance imaging scanner;

a vibration actuator supported by the headrest, wherein the vibration actuator is supported such that when the head of the subject is supported by the headrest, a vibration sound generated by the vibration actuator is coupled to an ear plug worn by the subject, and such that the vibration sound acoustically coupled to the ear plug is coupled to tissue surrounding the ear canal of the subject, thereby enabling the subject to hear the vibration by bone conduction; and

an audio circuit operatively connected to the vibration actuator for sending audio signals thereto.

In another aspect, a bone conduction acoustic communication device is provided, comprising:

an elongate fluid conduit comprising a lumen;

an inflatable balloon in fluid communication with the lumen of the elongate fluid catheter;

means for introducing a fluid into the elongate fluid conduit such that the balloon is inserted into the ear canal of the subject in a non-inflated state, and subsequently introducing a fluid into the elongate fluid conduit such that the balloon is inflated with the fluid and closes the ear canal, thereby providing isolation from external acoustic noise; and

an acoustic transducer contacting the elongate fluid conduit at a location remote from the balloon such that when the balloon is inflated within the ear canal, the acoustic transducer is in acoustic conductive communication with tissue surrounding the ear canal via fluid residing in the elongate fluid conduit and the balloon, thereby facilitating acoustic communication from and/or to a subject direction via bone conduction;

wherein the acoustic transducer is connectable to an audio circuit for transmitting and/or receiving audio signals.

In another aspect, there is provided an acoustic communication device for communicating in a noisy environment, the acoustic communication device comprising:

a noise isolating earplug including a distal elongated portion insertable into an ear canal of a subject such that when the distal elongated portion is inserted into the ear canal, the ear canal is closed over at least a portion thereof, thereby providing isolation from external noise;

an acoustic energy transducer in contact with and supported by the noise isolating earbud, wherein the acoustic energy transducer is supported such that when the distal elongated portion is inserted into an ear canal, the acoustic energy transducer is in acoustic conductive communication with tissue surrounding the ear canal via the distal elongated portion of the noise isolating earbud, thereby facilitating acoustic communication to and/or from a subject by bone conduction;

a headset configured to be worn on a head of a subject;

a vibration actuator supported by the headset, wherein the vibration actuator is supported such that when the headset is worn by a subject, vibrations generated by the vibration actuator are acoustically coupled to an ear plug worn by the subject, and such that vibrations acoustically coupled to the ear plug are acoustically coupled to tissue surrounding an ear canal of the subject, thereby enabling the subject to hear the vibrations through bone conduction; and

A further understanding of the functional and advantageous aspects of the present disclosure may be realized by reference to the following detailed description and the attached drawings.

Drawings

Embodiments will now be described, by way of example only, with reference to the accompanying drawings, in which:

fig. 1A-1E illustrate various exemplary implementations of an acoustic communication system in which a vibration actuator is in contact with an ear plug for acoustic coupling to a subject.

Fig. 2A-2B illustrate top views of two exemplary acoustic communication systems.

Fig. 3 illustrates an exemplary communication system in which a vibrating actuator is embedded within a headrest.

Fig. 4A-4B illustrate an exemplary communication system in which an acoustic channel is provided between each vibration source and an ear plug.

Fig. 5 illustrates an exemplary communication system, wherein the headrest includes a bone conduction microphone.

Fig. 6 illustrates an exemplary communication system in which a vibration actuator is disposed in a sound-deadening region.

Fig. 7-8 illustrate exemplary communication systems in which the headrest is formed from a variety of materials to reduce acoustic coupling between the vibration actuator and the bone conduction microphone.

Fig. 9A illustrates an exemplary communication system in which the headrest is formed of a material that includes air channels in order to reduce acoustic coupling between the vibration actuator and the bone conduction microphone.

Fig. 9B-9E illustrate various different headphone configurations and vibration actuator support mechanisms.

Fig. 10A, 10B, and 11-14 illustrate various exemplary earplug configurations.

Fig. 15A-15D illustrate an exemplary embodiment that includes the use of a fluid-filled balloon as an earplug.

Fig. 16A-16B illustrate various exemplary embodiments in which a fluid-filled catheter is used to acoustically couple a vibration actuator to a fluid-filled balloon that is inflated within an ear canal.

Fig. 17-22 illustrate various exemplary implementations of lorentz-based vibrating transducers.

Fig. 23-29 illustrate various active earplug devices in which a plurality of acoustic transducers are integrated with noise isolating earplugs to enable bi-directional communication.

Fig. 30A-30C, 31 and 32 illustrate an exemplary embodiment in which one or more acoustic transducers are disposed within a housing that is acoustically coupled to a noise isolating earplug.

Fig. 33-34 illustrate exemplary implementations for electrically interfacing with an acoustic transducer housed within a noise isolating earplug.

Fig. 35 illustrates an exemplary embodiment in which the vibration actuator is supported by an earmuff band or earmuff to bring the vibration actuator into contact with an ear plug worn by the subject.

Figures 36A-36B illustrate an exemplary embodiment of a headset-based acoustic communication device that is small enough to be used with a head coil of a magnetic resonance imaging scanner.

Detailed Description

Various embodiments and aspects of the disclosure will be described with reference to details discussed below. The following description and drawings are illustrative of the present disclosure and are not to be construed as limiting the present disclosure. Numerous specific details are described to provide a thorough understanding of various embodiments of the present disclosure. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of embodiments of the present disclosure.

The terms "comprises" and "comprising," as used herein, are to be construed as inclusive and open ended, and not exclusive. In particular, the terms "comprises" and "comprising," as used in the specification and claims, and variations thereof, are meant to encompass the specified features, steps or components. These terms are not to be interpreted to exclude the presence of other features, steps or components.

The term "exemplary" as used herein means "serving as an example, instance, or illustration," and should not be construed as preferred or advantageous over other configurations disclosed herein.

The terms "about" and "approximately" as used herein are intended to encompass variations that may exist in the upper and lower limits of a range of values, such as variations in properties, parameters, and dimensions. The terms "about" and "approximately" mean plus or minus 25% or less, unless otherwise specified.

It will be understood that, unless otherwise indicated, any given range or group is a shorthand way of referring individually to each member of the range or group and each and every possible sub-range or sub-group contained therein, and similarly for any sub-range or sub-group therein. Unless otherwise indicated, the disclosure refers to and explicitly incorporates each specific member and sub-range or sub-group combination.

The term "order of magnitude," when used in connection with a quantity or parameter, is intended to mean a range spanning from about one tenth to ten times the quantity or parameter.

Various exemplary embodiments of the present disclosure provide systems, devices and methods for facilitating communication in noisy environments, such as within and near Magnetic Resonance Imaging (MRI) scanners. Referring to fig. 1A, the auditory anatomy featuring an ear 100, ear canal 105, tympanic membrane 110, and temporal bone 115 is shown. Also shown is an earplug 120 that closes (blocks) the ear canal so that the earplug 120 provides passive protection for the wearer against noisy ambient noise. A vibration actuator 210 is provided that contacts the earplug 120 and is capable of generating vibrations at audio frequencies. Due to the contact between the vibration actuator 210 and the earplug 120, vibrations from the vibration actuator 210 are transferred to the earplug 120, the vibrations being conducted to the temporal bone 115 so that they are heard as sound by the wearer.

While the ear bud 120 provides acoustic insulation from noisy ambient noise, the audio vibrations generated by the vibration actuator 210 are conducted to the ear bud 120 and through the ear bud 120. These vibrations are conducted through the earplug 120 to the temporal bone 115 and surrounding soft tissue, conduct sound to the inner ear, and can be clearly heard by the patient through bone conduction.

Without being limited by theory, it is believed that although bone conduction is the primary mechanism by which the patient can hear the sound generated by the vibration actuator 210, the transmission of vibration energy from the proximal side of the earplug 120 into the air, such that the generation of sound waves in the air within the ear canal (and subsequent stimulation of the tympanic membrane) can provide a secondary mechanism for sound conduction. Both of these acoustic energy transduction mechanisms employ conduction of vibration from the vibration actuator 210 to the earplug via direct physical contact between the vibration actuator 210 and the earplug 120 or via indirect acoustic contact via an intermediate medium that is also capable of conducting acoustic vibration.

The vibration actuator 210 shown in fig. 1 may be any device that generates vibrations from any type of electrical or mechanical input. Examples include, but are not limited to, piezoelectric crystals, piezoelectric actuators, piezoelectric benders, and magnetic speakers.

In one exemplary embodiment, which will be described in further detail below, the vibration actuator 210 may be a Lorentz speaker for use in the static (main field; B) of an MRI environment₀) A magnetic field. The lorentz loudspeaker comprises a membrane having electrical traces defined thereon. When placed in a magnetic field, such as the magnetic field of an MRI scanner, lorentz forces are generated when current passes through the traces. When the frequency of the current is an audio frequency, acoustic vibration of the membrane is generated.

In one exemplary implementation, the earplug 120 may be formed of or include a viscoelastic polyurethane foam (e.g., "memory" foam; low-elasticity foam), wherein the foam is compressed for insertion into the ear canal and expanded to engage the ear canal to provide effective passive noise cancellation. Earplugs made from viscoelastic polyurethane foam typically have passive noise protection of up to 35 dB. Viscoelastic polyurethane foams (memory foams) have certain material properties that soften when heated to 37 degrees celsius (human body temperature) and can therefore be shaped into warm bodies, such as the cavities of the ear canal. In addition, memory foams have the property of recovering their original molded shape. Viscoelastic polyurethane foam is a suitable material for earplugs and is typically provided as a cylindrical body of viscoelastic polyurethane foam that can be compressed and inserted into the ear canal. Upon insertion, the foam expands and molds to the ear canal to form a secure and uniform contact closure on the inner surface of the ear canal.

In alternative exemplary implementations, other materials may be employed to fit the ear canal to provide passive noise isolation. Non-limiting examples of such materials include wax, silicone, non-memory foam, and soft plastic.

In some exemplary implementations, the earplug may be formed to have structural features that allow for easy insertion while closing the ear canal. For example, referring to fig. 1B, an earplug is shown wherein the ear canal insertable portion of the earplug includes one or more flexible ridges configured to mechanically support the earplug in the ear canal while closing the ear canal. Such ridges may be constructed of a flexible material including, but not limited to, silicone or a flexible thermoplastic.

As described above, the earplug 120 is capable of conducting or transmitting vibrations at audio frequencies such that vibrations generated by the vibration actuator 210 are conducted to the temporal bone, thereby facilitating the formation of an acoustic path within the ear canal that is capable of bone conduction.

As described above, the earplug 120 facilitates the conduction of vibrations to the temporal bone. To ensure efficient transmission of pressure waves propagating in a direction parallel to the earplug-temporal bone interface, the earplug is configured to provide mechanical contact with tissue near the temporal bone. This may be accomplished by providing an earplug whose size, shape and/or resilience causes an outer surface of the insertable portion of the earplug to be in physical contact with an inner surface of the ear canal for at least a portion of the length of the ear canal.

To facilitate efficient transmission of pressure waves propagating in a direction perpendicular to the earplug-temporal bone interface, the earplug may be made of a material having a density similar to (e.g., within the same order of magnitude; i.e., within a factor of 10) that of the ear canal and surrounding tissue of the temporal bone. For example, the inventors have found that earplugs made from viscoelastic foam having a mass density of 0.25g/cc effectively couple the sound that can be heard by the wearer. Suitable coupling is expected to be achieved for materials having a mass density in the range of about 0.2g/cc to about 20 g/cc. As another illustrative example, a porous material having a density similar to air (0.001 g/cc) may not effectively couple the sound that a wearer can hear. Examples of such materials include, but are not limited to, viscoelastic memory foams as described above, or plastics, waxes, thermoplastics, polymers or composites of these materials.

It should be understood that the vibration actuator 210 shown in fig. 1A and 1B may be in contact with the earplug 120 according to various embodiments and implementations. Further, as described in detail below, it should be understood that the vibration actuator 210 need not be in direct mechanical contact with the earplug 210, and one or more additional solids or liquids may be provided between the vibration actuator 210 and the earplug 120 to facilitate coupling (transfer) of the vibration generated by the vibration actuator 210 to the earplug 120 (in the absence of sound propagation in air). In other words, the vibration actuator 210 may be in acoustic conductive communication with the earplug 120 through direct contact or through indirect contact of one or more acoustic coupling materials or structures. As described further below, the one or more acoustic coupling materials may be selected to have respective acoustic impedances that support efficient acoustic conduction of vibration from the vibration actuator 210 to the earplug 120.

In some exemplary embodiments, the vibration actuator 210 is supported by an external support such that when the patient's head is in contact with the external support, the acoustic vibrations generated by the vibration actuator 210 are conducted to the ear buds 120 (in the absence of sound propagation in the air). For example, as described in several exemplary embodiments below, the vibration actuator 210 may be attached to, embedded in, or otherwise supported by the headrest such that when the head of the patient is supported by the headrest, the acoustic vibrations generated by the vibration actuator 210 are coupled to the ear buds.

In other exemplary embodiments, active earplugs are described in which a vibration actuator is attached to, embedded in, integrated into, or otherwise supported by the earplug.

In some exemplary embodiments, multiple vibration sources may be provided, as shown in fig. 1C and 1D. This will ensure that proper contact is achieved between the vibration source and the ear plugs without the need for cumbersome manipulation of the patient's position. One configuration includes an array of rigid vibration sources 215, some of which will be in more uniform or complete contact with the earplug. This may be determined by contacting an array of pressure transducers 216 with a vibration source, the pressure transducers 216 may be formed by piezoelectric strain gauges or load cells. The pressure transducer array and vibration source may be mounted on a rigid plate 218 and electrically connected to their respective amplifiers through the rigid plate 218. Each vibration source will be powered by an audio amplifier 219 and the signal from each pressure transducer will be detected and amplified by an array of preamplifiers 221.

After the array is placed in the outer ear of the patient, the signals from the pressure transducers will be sampled and the transducer with the largest contact pressure will be selected from the pressure transducers to transmit the vibration source. Alternatively, more than one vibration source may be actuated depending on the pressure profile detected from the pressure transducer. These signals will be analyzed by the audio electronics 217 and the audio signals will be delivered to the patient.

To ensure proper transmission of vibrations to the earplug, a material of suitable density and stiffness may be inserted between the earplug and the vibration source, as shown in fig. 1E. The impedance matching layer 50 will be bonded to the patient side of the vibration source 210 and placed in contact with the ear plug 120.

Fig. 2A illustrates an exemplary embodiment of a headrest-based communication system for use during an MRI scan. A head support headrest 200 for use within an bore of an MRI scanner supports the head 130 of a patient. The vibration actuator 210 is incorporated (e.g., recessed) into the headrest 200 such that when the head 130 of the patient is supported by the headrest 200, the vibration actuator 210 is in physical contact with the outer surface of the ear bud 120 worn by the patient. The communication headrest 200 may be used to facilitate communication of a scanning technician with a patient, and may additionally or alternatively be used to allow the patient to experience entertainment content, such as music, audio books, or movies, during a scanning operation of the MRI scanner.

Although the vibration actuator 210 is shown as being recessed (embedded) into the headrest 200, the vibration actuator 210 may alternatively be attached to a surface of the headrest 200 adjacent to the location of the patient's ear.

As shown in fig. 2A, each vibration actuator is electrically connected to an amplifier 215 and electronics 220, the electronics 220 being designed to vibrate the vibration actuator 210. For example, where the vibration actuator 210 is a piezoelectric device, a class G ceramic speaker driver such as MAX9788 may be used to drive the device based on an audio signal provided by a bluetooth receiver module. In the case where the vibration actuator is a lorentz speaker, a class a or class a/B amplifier such as MAX98309 may be used to drive the device based on the audio signal received from the bluetooth receiver module. It should be understood that one skilled in the art will be able to select the appropriate electronics for a particular type of vibration actuator 210.

In some exemplary implementations, each vibration actuator 210 can be spatially offset from where the headrest 200 contacts the earplugs 120 as long as vibration energy is conducted to the earplugs through the intermediate material without significant attenuation. For example, in one non-limiting exemplary embodiment, the vibration actuator 210 may be placed between 1cm and 20cm, and depending on the material properties of the headrest 200, the spatial offset may cause the vibration to be attenuated between-0.01 and-20 db, thereby still being able to transfer a non-negligible amount of vibration energy to the earplug 120. Furthermore, the damping may be compensated by increasing the power of the vibration actuator 210.

While many of the exemplary embodiments of the present invention show dual actuator embodiments involving vibration actuators on both sides of the head, it should be understood that any of the embodiments may be adapted to provide a single-sided version with one or more vibration actuators on one side of the head. Fig. 2B shows an example of such an embodiment.

One such exemplary embodiment is shown in fig. 3, wherein the vibration actuator 210 is embedded within the headrest 200 and is spatially offset from where the headrest is in contact with the earbuds 120, such that the headrest material between the vibration actuator 210 and the earbuds 120 provides a coupling medium that indirectly places the vibration actuator 210 in acoustic conductive communication with the earbuds 110. Unlike the exemplary embodiment shown in fig. 2A, in which the vibrations generated by each vibration actuator are directly coupled to each earplug, the vibrations generated by the vibration actuators 210 shown in fig. 3 are conducted through a length of headrest material before being transmitted onto the outer surface of the earplugs 120.

In one exemplary implementation, the acoustic impedances of the headrest material and the earbud material can be selected to achieve effective vibration energy transfer between the headrest 200 and the earbuds 120. Impedance mismatches can result in acoustic reflections and inefficiencies. For example, the materials may be selected such that the coefficient of transfer of acoustic power through the material interface is greater than 20%, where the coefficient of transfer of acoustic power may be calculated as 1- [ (Z)_headrest+Z_earplug)/(Z_headrest-Z_earplug)]²Wherein Z is_headrestIs the acoustic impedance of the headrest, Z_earplugIs the acoustic impedance of the earplug material. This condition is met if the acoustic impedances of the headrest material and the earplug material differ by a factor of 10 or more from each other.

It should be understood that while the vibration actuators 210 are shown in many exemplary embodiments as being aligned such that the resulting vibrations emanate parallel to the longitudinal axis of the earplugs 120, the vibration actuators 210 may be offset or rotated relative to the longitudinal axis of each earplug, so long as such offset or rotation does not result in significant acoustic coupling loss.

Fig. 4A illustrates an alternative exemplary embodiment in which a sound conduit 230 (e.g., a post or other component) of a sound conducting material is embedded within the headrest 200 to facilitate the acoustic conduction of vibrational energy from the vibration actuator 210 to the earbud 120. The acoustic conduit 230 is formed of an acoustically conductive material selected to facilitate the conduction of acoustic energy from the vibration actuator 210 to the earplug 120. Examples of suitable materials for forming the acoustic conduit 230 include, but are not limited to, materials that are capable of conducting vibrational energy to the earplug without attenuating the energy by more than 20db and acoustically matched such that the transfer coefficient of the vibrational energy is at least 20%. Non-limiting examples of such materials include wax, silicone, non-memory foam, and soft plastic.

The acoustic conduit 230 can be arranged such that its distal end is located at or adjacent to the outer surface of the headrest. In one exemplary implementation, the distal end of the acoustic conduit 230 may be located on the headrest surface. In another exemplary implementation, the distal end of the acoustic conduit 230 may protrude (extend) outward from the headrest surface.

Fig. 4B illustrates an alternative exemplary embodiment in which an acoustic conduit 230 extends through the headrest 200 to provide an acoustic conduction path (channel, conduit) between the vibration actuators 210 that are located on or beyond the outer surface of the headrest 200 (or recessed into the outer surface of the headrest 200).

In some embodiments, the headrest communication system can be adapted to support two-way (two-way) communication by integrating a bone conduction microphone into the headrest, such that the headrest is able to transmit acoustic vibrations to the patient through contact between the vibration actuator 210 and the ear buds 120, and is also able to detect voice produced by the patient through the bone conduction microphone.

Fig. 5 illustrates an example of such a headrest-based communication system, where a headrest 200 is shown supporting a head 130 of a patient, where the headrest 200 includes an embedded vibration actuator 210 in contact with an ear-piece 120 worn by the patient and a bone-conduction microphone embedded in the headrest 200. The bone conduction microphone 240 is in contact with the back of the brain of the patient to be able to receive the patient's voice. During speech, vibrations originating from the vocal cords are transmitted to skeletal structures, such as the skull. These vibrations may be detected by the bone conduction microphone 240 and converted to electrical signals for presentation as speech. Because voice sensing is performed based on acoustic vibrations, as opposed to the propagation of sound waves in air, the bone conduction microphone 240 has poor sensitivity to ambient noise in the form of propagating sound waves. The bone conduction microphone 240 is therefore insensitive to the noisy noise of the MRI scanner, enabling efficient communication between the patient and other individuals (e.g., a scanning technician) during operation of the MRI scanner. It should be appreciated that the bone conduction microphone may be integrated with any of the foregoing exemplary headrest communication systems and variations thereof.

The exemplary embodiment illustrates an acoustic communication system in which two-way acoustic communication is facilitated without acoustic wave propagation, whereby the vibration actuator 210 and the bone conduction microphone 240 are capable of acoustic communication based on acoustic conduction of vibrations to and from the patient.

It should be understood that the bone conduction microphone 240 may be implemented in accordance with various acoustic transducers suitable for detecting acoustic vibrations. For example, in some non-limiting example implementations, the vibration microphone 240 may include an accelerometer, a velocity sensor, a proximity probe, a piezoelectric crystal, or a piezoelectric bender.

Alternatively, in another exemplary implementation, the bone conduction microphone may be implemented using a lorentz microphone, wherein the lorentz acoustic speaker is used in a reciprocating mode in which an electrical potential is induced through a conductor that vibrates in the magnetic field of the MRI. In this example, the bone conduction microphone 240 may be operably connected to additional electronics 245, including but not limited to an amplifier, a processor, and/or a wireless transmitter. It should be understood that one skilled in the art will be able to select the appropriate electronics associated with the particular type of bone conduction microphone used in a given implementation.

Referring to fig. 6, an exemplary embodiment is shown in which the vibration actuators 210 are supported within respective sound isolation regions (e.g., chambers) 250, the sound isolation regions 250 also being embedded within the headrest 200 (or recessed within the headrest 200). The sound isolation region 250 reduces the intensity of vibrations coupled into the headrest 200 from the vibration actuator 210 in a direction different from the direction between the vibration actuator 210 and the ear buds 120, thereby reducing the intensity of parasitic vibrations detected by the bone conduction microphone 240.

An acoustic conduit 230 formed of an acoustically conductive material (as described above) may also be embedded in the headrest 200 to provide an acoustic conduction path for conducting vibrations from the vibration actuator 210 to the ear bud 120. In the exemplary embodiment shown in fig. 6, each sound tube 230 extends through an aperture in the wall of the sound-deadening region 250. According to various non-limiting exemplary implementations, sound-deadening regions 250 may be formed by regions of substantially reduced mass density, such as fully evacuated chambers, volumes of filament mesh, chambers of stiff, massive walls. Alternatively, the acoustic isolation chamber can be formed using walls made of a high density material such that an acoustic impedance mismatch between the headrest material and the wall material of the acoustic isolation chamber results in a transfer coefficient of less than 50% or less.

This exemplary embodiment also shows an acoustic communication system in which acoustic communication is facilitated without acoustic wave propagation, whereby the vibration actuator 210 and the bone conduction microphone 240 are able to communicate acoustically based on acoustic conduction of vibrations to and from the patient.

Referring now to fig. 7, an exemplary headrest-based communication system is illustrated in which headrest 200 includes different regions formed of different materials (this figure illustrates an exemplary implementation involving two different materials). In the exemplary implementation shown in the figures, the headrest 200 includes a base portion 260 formed of a first material, wherein the base region is located on the back side of the patient's head (e.g., in this example, the base region supports the bone conduction microphone 140), and two side portions 265 formed of a second material, wherein the side portions 265 support the vibration actuator 210. The first material may be selected to have cushioning properties to provide patient comfort. Non-limiting examples of suitable materials include compressible foam or memory foam. The compressible foams may be selected such that they do not compress to less than 10% of their non-compressed thickness under the weight of the patient's head (soft enough, but to ensure that the patient's head does not contact the table). The second material may be selected to exhibit mechanical properties (e.g., rigidity and/or elasticity) that enable the vibration actuator 210 to make firm contact (e.g., contact suitable for effective acoustic conduction) with the ear bud 120 when the head 130 is supported by the base 260 of the headrest. Non-limiting examples include incompressible materials.

In some exemplary implementations, the physical properties of the two materials may be selected such that they have different acoustic impedances. For example, the materials may be selected such that the coefficient of transfer of vibrational energy from one material to another is less than 50%. The different acoustic impedances will create an impedance mismatch boundary 275 between the base 260 (housing the bone conduction microphone 240) and the side 265 (housing the vibration actuator 210) so that waves propagating from the vibration actuator 210 to the bone conduction microphone 240 will experience reflections, thereby reducing the amount of acoustic coupling between the vibration actuator 210 and the bone conduction microphone 240.

Fig. 8 illustrates another exemplary embodiment wherein the headrest 200 includes a sound isolation region between the vibration actuator 210 and the bone conduction microphone 240. As in the exemplary embodiment shown in fig. 7, different materials may be used for the central base region 262 on the back side of the head and the side regions 265 adjacent to the patient's ears (alternatively, the same material may be used for the side regions 265 and the central base region 262). In this example, the sound isolation region 264 is disposed between the side regions 265 and the central base region 262, where the sound isolation region 264 includes a material that isolates the vibration actuator 210 from the bone conduction microphone 240. For example, sound-deadening region 264 may be formed of a very dense material, such as, but not limited to, neoprene, which is selected to form a sound-deadening barrier such that the inefficient transmission coefficient through the boundary is less than 50%. In another example, the acoustically isolated regions may be formed from a material having an attenuation coefficient greater than-0.5 db/cm to reduce acoustic conduction between the actuator and the microphone. Non-limiting examples include very low density porous foams, evacuated or inflated regions.

Referring now to fig. 9A, an exemplary headrest-based communication system is provided wherein headrest 200 includes two sound isolation channels 270. The channel is located between the vibration actuator 210 and the bone conduction microphone 240, thereby reducing the amount of acoustic coupling between the vibration actuator 210 and the bone conduction microphone 240. This reduction in acoustic coupling is achieved by removing headrest material that would otherwise conduct vibrations from the vibration actuator 210 to the bone conduction microphone 240. It should be understood that the exemplary implementation shown in fig. 9A is provided to illustrate one non-limiting example of the many different possible channel geometries that may be formed in a headrest to reduce or prevent acoustic conductive coupling between the vibration actuator 210 and the bone conduction microphone 240. Various alternative channel and cut-out configurations may be employed to increase the effective path length between the vibration actuator 210 and the bone conduction microphone 240.

Referring to fig. 9B, an exemplary headrest-based communication system is illustrated in which the vibration actuator 210 for contacting the ear buds 120 worn by the patient is supported by a support frame 280, the support frame 280 being physically separate from the headrest 200 housing the bone conduction microphone 240. Separating the vibration actuator 210 from the headrest portion 240 has the advantage of reducing coupling between the vibration actuator 210 and the bone conduction microphone 240.

In some exemplary embodiments, one or more positioning mechanisms may be integrated into the support frame 280 to facilitate adjusting the position at which the vibration actuator 210 is supported to accommodate a range of head sizes.

The head support and ear conduction device should be positioned relative to the patient to ensure sufficient pressure on the earplug to maximize occlusion of the ear canal without causing discomfort to the patient. This may require some adjustment of the device to accommodate different patient sizes, positions and shapes. Thus, in some exemplary embodiments, the head support may be configured to provide a mechanical structure to allow positioning of the vibration source (e.g., three degrees of freedom of motion). As shown in fig. 9C, the vibration source 210 may be mounted at the end of a support arm 282, and the support arm 282 may rotate about a pivot 284. The pivot 284 may be spring loaded to maintain compression of the vibration source on the sound attenuating earplug.

In this exemplary embodiment, the patient's head rests on a head support 200 made of soft memory foam, which head support 200 in turn supports a bone conduction cranial microphone 240. The head support 200 rests on top of the mounting frame 290 as shown in the cross-sectional view. The mounting frame has attached a sliding pivot arm connector 292. The slider is shown in the form of a closely fitting ramp which allows the support arm to move and pivot in a vertical direction. Thus, by virtue of the vertical movement of the support to pivot arm connector 292 and the rotational movement of the support arm 282, the vibration source 210 can be accurately positioned over the ear and the anti-rattle ear plug regardless of the patient's physical habits or head orientation.

To facilitate accommodation of the patient's position in the cranio-caudal (CC) direction, the head support 200 provides another adjustment as shown in fig. 9D. The pivot arm extends over a linear bearing 294, the linear bearing 294 being slidable on a shaft 296 and designed to maintain the spring loaded characteristic of the pivot arm load. This allows the vibration source 210 position of the supporting arm to be adjusted in the CC direction.

To ensure efficient conduction of vibrations to the patient, the vibration source may be held on a fixed rigid frame, as shown in fig. 9E. One way to achieve this is to construct it using a rigid cylinder 10 that surrounds the head of the patient. The patient's head will rest on the soft headrest while the earplug is inserted into the ear. The vibration source 210 will be connected to the cylinder by an adjustable connection 20, which adjustable connection 20 may comprise a threaded rod to allow the position of the vibration source to be changed by means of the knob 30.

In some embodiments, the ear bud worn by the patient is configured to completely enclose the ear canal of the wearer such that the ear bud extends across a cross-section of the ear canal for a portion of the ear canal length, thereby providing passive noise isolation (protection) against ambient noise. The earplug thus provides isolation from propagating sound waves (ambient noise) while facilitating physical contact (direct or indirect) with the vibration actuator to enable conductive acoustic communication as described above.

Fig. 10A shows an example of an earbud 300, the earbud 300 configured to close the ear canal while providing acoustic coupling between the vibration actuator 210 and the patient tissue. The exemplary earplug 300 is comprised of a distal elongated portion 302, the distal elongated portion 302 being configured to be insertable into an ear canal. The distal elongate portion 302 is formed of a compressible material such that when the distal elongate portion 302 is inserted into the ear canal, the distal elongate portion 302 completely occludes the ear canal over at least a portion of the ear canal while providing passive noise protection and facilitating acoustic conductive coupling with bone structures surrounding or adjacent the ear canal. As shown, the distal elongated portion 302 may be cylindrical or may have other shapes, so long as the shape is suitable for occluding the ear canal when the distal elongated portion 302 is inserted into the ear canal. In one exemplary embodiment, the distal elongate portion 302 of the earplug is formed of a viscoelastic polyurethane foam.

The example earplug 300 also includes a proximal acoustic coupling portion 304 that is configured to extend outwardly from the ear of the wearer when the distal elongated portion 302 is inserted into the ear canal. The proximal acoustic coupling portion 304 extends outward to contact the headrest 200 or the vibration actuator 120 such that vibrations generated by the vibration actuator 120 are acoustically conducted through the earplug 300 and into the bone tissue surrounding the ear canal. The proximal acoustic coupling portion 304 may be formed of the same material as the distal elongate portion, such as viscoelastic polyurethane foam. Alternatively, the proximal acoustic coupling portion 304 may be formed from a material having one or more different properties than the distal elongate portion 302.

In some exemplary implementations, the earplug 300 may be formed as a unitary structure or by joining the distal elongate portion 302 to the proximal acoustic coupling portion 304.

In some exemplary embodiments, the earplug 300 may be formed of a conductive material. In this case, if the contact points with the headrest 200 and/or the vibration actuator 210 are also electrically conductive, the conductive path (or paths if both earplugs are conductive) to the subject can facilitate detecting when proper contact has been established. In alternative exemplary embodiments, the headrest 200 can include one or more pressure sensors configured to determine whether sufficient pressure has been established between the headrest 200 and the earplugs during use.

The proximal acoustic coupling portion 304, although shown in fig. 10 as a cylindrical disk (e.g., a proximal acoustic coupling flange), can have a variety of shapes so long as the proximal acoustic coupling portion 304 is capable of contacting the headrest 200 and/or the vibration actuator 210 when the distal elongated portion 302 is inserted into the ear canal.

Fig. 10A shows the exemplary earplug of fig. 10A in contact with an exemplary cylindrical vibration actuator 210.

For example, as shown in FIG. 11, the proximal acoustic coupling portion may be spherical (or semi-spherical), as shown at 306.

In another exemplary embodiment, the proximal acoustic coupling portion 304 may be provided in an elongated shape having a longitudinal axis that is angled relative to the longitudinal axis of the distal elongated portion 302. For example, as shown in fig. 12, the proximal acoustic coupling portion may be provided in the form of a cylinder, as shown at 308, wherein the longitudinal axis of the cylindrical acoustic coupling portion 308 is orthogonal to the longitudinal axis of the distal elongate portion 302.

It will be apparent to those skilled in the art that many alternative shapes may be employed for the proximal acoustic coupling portion and the distal elongate portion. For example, the distal elongate portion of the earplug may include a plurality of closure structures. The closure structure may extend radially from the central elongate member. Fig. 13 illustrates an exemplary implementation in which the distal elongate portion includes a plurality of closure discs 310, the closure discs 310 being spaced longitudinally along the distal elongate member 312 and extending in a radial direction from the distal elongate member 312. The closure disc 310 can facilitate closure of the ear canal, mechanically support the earplug within the ear canal, and facilitate acoustic coupling with tissue structures surrounding the ear canal.

In some exemplary implementations, the distal elongate portion and the proximal acoustic coupling portion of the earplug may be formed of the same material. Alternatively, the distal elongate portion and the proximal acoustic coupling portion may be formed from a variety of materials to improve the function of the earplug. In some exemplary implementations, one or both of the distal elongate portion and the proximal acoustic coupling portion can be made of a variety of materials.

Fig. 14 illustrates an exemplary earplug made using two different materials, showing a cross-sectional view in which a first material forms a peripheral region 320 of the earplug and facilitates efficient coupling of vibrations from the earplug to tissue. The first material may be selected to have a density similar to the tissue surrounding the ear canal and temporal bone (e.g., within the same order of magnitude; e.g., within a factor of 10) in order to achieve effective acoustic coupling from the earplug to the tissue surrounding the ear canal. However, in order to provide sufficient compressibility to the earplug to facilitate insertion and maintain sufficient contact between the first material and the tissue, a second material may be used to form a central (e.g., core) region 325 of the earplug. The second material may have a lower density while having a higher compressibility and/or elasticity than the first material. Examples of desirable materials include, but are not limited to, semi-compressible foam. The purpose of the semi-compressible foam is to apply pressure to the ear canal to increase friction between the first material and the ear canal, thereby increasing the transmission of vibrations from the earplug to the temporal bone. The core material may also be selected to provide noise isolation, while the peripheral portion provides acoustic coupling between the temporal bone and the vibration actuator.

An alternative to sound actuation via bone conduction is to insert a device similar to a balloon catheter into the ear canal, as shown in fig. 1. The tip of the catheter is an inflatable balloon, which is constructed of a material such as flexible rubber, alternatively may be made of other materials such as latex. The balloon is deflated in the original state and small enough to be inserted into the ear canal. By using a syringe or similar pressure inducing device, a fluid such as sterile water may be pumped through the tube into the balloon. This will serve to fill the balloon with sterile water, thereby closing the ear canal as a passive noise reduction system.

Thus, in some exemplary embodiments, at least a portion of the earplug may be filled with an incompressible liquid that provides a noise-isolating closure of the ear canal while also providing acoustic coupling for conducting vibrations from the vibration actuator to the tissue surrounding the ear canal. For example, as shown in fig. 15A and 15B, an earplug assembly is shown that includes a flexible catheter having an elongated sheath defining at least one lumen 350, where the lumen 350 is in fluid communication with an inflatable balloon 360 at or near a distal end of the elongated sheath. The proximal end of the catheter is connected or connectable to a syringe 370 or other device capable of increasing the pressure within the balloon 360 to inflate the balloon.

As shown in fig. 15C and 15D, the distal portion of the elongate sheath may be inserted into the ear canal with balloon 360 initially in an uninflated state. When fluid is injected into the lumen 350 under pressure applied by the syringe 370, the balloon 360 is filled with the fluid and expands such that the outer surface of the balloon 360 is in contact with the inner surface of the ear canal. The fluid used to fill the balloon may be, but is not limited to, fluids such as water, saline, and mineral oil. The fluid-filled balloon 360 provides passive noise isolation by filling and sealing the ear canal with a dense material. The distal portion of the elongate sheath may be configured to inflate the lumen toward the balloon 360 and/or within the balloon 360, thereby reducing acoustic reflections.

The catheter portion may be formed from materials such as, but not limited to, PEEBAX, silicone rubber, nylon, polyurethane, polyethylene terephthalate (PET), latex, and thermoplastic elastomers. The balloon portion 360 of the apparatus may be constructed using materials similar to those used in the manufacture of angioplasty balloons. Non-limiting examples include flexible PVC (polyvinyl chloride), polyethylene terephthalate (PET), and nylon.

Fig. 16A illustrates an exemplary communication device utilizing the balloon catheter earplug of fig. 15A-15D. As shown in fig. 16, a portion of the catheter is in contact with one or more vibration-actuated devices 210. This contact creates vibrations that propagate along the catheter toward the distal balloon 360. Hearing of the patient is achieved by generating vibrations directed into the earplug using one or more vibration actuators 210, the vibration actuators 210 being remote from the earplug device in contact with the fluid-filled conduit. The bottom side of the vibration actuators are illustrated as being fixed to a mass that does not move so that all of their vibrational energy is transferred to the conduit.

In an alternative exemplary embodiment, the plunger of the syringe shown in fig. 16A may be adapted to include a sound-producing element, such as a loudspeaker diaphragm or a piezoelectric transducer, to enable direct excitation of longitudinal sound waves in the lumen of the elongate sheath.

Fig. 16B shows an alternative exemplary embodiment in which the conduit runs into a rigid waterproof chamber 380 containing electromechanical actuators 380. The actuator may be constructed of a piezoelectric material such that under electrical stimulation, the actuator will expand. The actuator will be powered through the audio amplifier 390, the audio amplifier 390 being connected to the actuator through the chamber. When the audio signal from the amplifier causes expansion and contraction of the actuator, the fluid surrounding the actuator will experience a change in oscillator pressure that is conducted along the catheter to the ear canal and balloon. This will cause the balloon to undergo a vibratory oscillation that will be conducted into the auditory system of the patient by bone conduction or tympanic membrane.

In the foregoing exemplary embodiments, the vibration actuator is described as being located within or on a headrest that supports the head of the patient such that the vibration actuator makes acoustic contact with a passive earbud worn by the patient. The following alternative exemplary embodiments are directed to active earplugs having integrated vibration actuators.

Referring to fig. 17, an example of an active earplug is shownAn exemplary embodiment, wherein the foam earplug 400 is shown having a substrate 405 attached or adhered thereto, wherein the substrate 405 contains one or more conductors (e.g., conductive paths or traces) that act as lorentz vibration actuators. A current I flows in each conductor in the direction indicated by the arrow 401 in the figure. The circular base plate 405 is positioned such that when the active ear plug is worn by a patient, the conductor is in relation to the main static magnetic field B of the MRI scanner₀At an angle (preferably perpendicular). Conductors 410 are each oriented perpendicular to the static magnetic field B₀And the direction of the current experiences a lorentz force F, according to the following equation:

F＝I∫dl×Bo (1)

the lorentz force acting on the conductor 410 displaces the substrate. When an alternating current is applied to the traces at an audio frequency, the substrate is responsively displaced at the same frequency, thereby generating a propagating pressure wave. Due to the contact between the substrate and the earplug, the pressure wave is conducted through the earplug and onto the bone surrounding the ear canal, so that the pressure wave generates an audible sound that is perceptible to the wearer of the earplug.

As mentioned above, the conductive traces need not be oriented perpendicular to the static magnetic field of the MRI scanner. If the ear plugs are worn such that the conductors are not perpendicular to the main static field of the MRI scanner, a current component on the conductive traces perpendicular to the direction of the magnetic field will displace the substrate.

It should be noted that the substrate on which the conductors are attached need not be rigid, and may be a flexible substrate made of materials including, but not limited to, polyimide (Kapton), plastic, and any type of flexible polymer, so long as the substrate is attached, adhered, affixed, pressed against, or otherwise in mechanical contact with the earplug such that vibrations originating from the substrate can be transmitted to the earplug.

In one exemplary implementation, the substrate and conductive traces may be formed using a flexible printed circuit board, where appropriate conductor patterns are etched on a sheet of copper clad laminate. Alternatively, in alternative exemplary implementations, the conductors may be attached directly to the earplug without an intermediate substrate.

FIG. 18 illustrates an exemplary implementationIn a manner wherein the conductive traces 410 are oriented such that when the patient wears the earbuds in a magnetic resonance scanner, the conductive traces 410 are relative to a static field (B) of the MRI scanner₀Field) at an angle (preferably perpendicular). As shown, the conductive traces 410 are connected in parallel by line segments 415. When an alternating voltage is applied to terminals (420 and 422) located across conductive trace 415, current flows through the conductive trace. Lorentz forces applied to the conductive traces 410 displace the substrate 405, thereby generating a pressure wave that will be heard by the wearer through bone conduction. The conductive traces 415 may be comprised of any suitable conductive material. Examples include, but are not limited to, copper, tin, silver, or gold.

Referring to fig. 19, an exemplary embodiment of an active earplug 400 is shown having an attachment conductor 430 comprised of a solid planar portion of conductive material. Two electrodes (432 and 434) are located on either side of the conductive plane. The current flowing between the two electrodes is distributed in a plane, thereby also generating a distributed lorentz force on the electrically conductive locations.

Referring to fig. 20, an exemplary embodiment of an active earplug 400 is shown in which a series of vertical conductive traces 440 attached to a flexible film are connected to each other in series (as opposed to parallel as shown in fig. 18). As shown at 442 and 444, there are additional conductors to connect the conductive traces such that the current in the conductor traces flows in the same direction in all of the vertical traces, such that the lorentz forces generated on the vertical traces flow in the same direction on the substrate surface. Additional conductive traces connecting the vertical traces are purposely placed at the perimeter of the substrate. Despite the presence of areas on the peripheral conductors where the lorentz forces oppose the lorentz forces of the vertical conductors, the total net lorentz force on the substrate is still present. If a flexible substrate is used, the Lorentz force profile may cause characteristic bending of the substrate. In general, vibrations are still generated and conducted through the earplug material. An advantage of the series connection of the vertical traces is that less current on the terminals is required to generate an equivalent lorentz force on the substrate surface. In this example, the additional conductors connecting the central vertical trace 440 are shown as additional traces attached to the substrate (e.g., traces that would be present on a printed flexible circuit), but it should be understood that these additional conductors may alternatively be provided in the form of electromagnetic wires, insulated copper wires, or any other type of conductor.

It should be understood that the conductive traces in fig. 18 and 20 are illustrated as vertical traces for simplicity, since the traces are perpendicular to the main static field (B) of the MRI_o). However, those skilled in the art will appreciate that the current vector associated with the conductive traces need only have a component perpendicular to the magnetic field in order to produce a lorentz force on the conductor. Alternative exemplary embodiments may employ several patterns of conductor traces that generate lorentz forces that will cause displacements on the substrate, thereby generating sound.

In the previous figures, the conductors are illustrated as being located on the outer surface of the earplug. Referring to fig. 21, the earplug is shown with the conductor 410 embedded inside the earplug 400, rather than on the outer surface of the earplug 400.

The exemplary embodiments shown in fig. 18-20 are described as being capable of producing sounds that can be heard by the wearer through bone conduction. However, the active components shown in fig. 18-20 may additionally or alternatively be used to sense vibrations generated by the wearer of the earplug during speech.

During speech, vibrations originating from the vocal cords are transmitted to skeletal structures, including the bones along the length of the ear canal. Referring to fig. 22, an active earplug 400 is shown that incorporates a series of vertical conductors 410 on a substrate 405. During speech, the wearer causes small vibrations on the earplug 400, which causes the substrate and the conductor 410 formed thereon to also vibrate. A voltage V will be induced across each conductor 410 that is perpendicular to the main static field (B) of the MRI_o) Is proportional to the component of the velocity v in the direction of (a), according to the following equation:

V＝v∫dl×Bo. (2)

the time-varying voltage across conductor 410 is proportional to the amplitude of the vibration and appears as speech. Thus, the device may be used as a microphone and as an input for a recording or audio communication system.

It will be appreciated that several types of conductor configurations are possible for forming a microphone on an earplug. These configurations include, but are not limited to, those shown in fig. 18-20.

There are several advantages to using the microphone configuration provided according to the present disclosure in an MRI environment. Because voice sensing is performed based on vibration, the device is inherently insensitive to ambient noise. It is therefore insensitive to the noisy noise of the MRI scanner and will enable efficient communication during operation of the MRI scanner. It should again be noted that although the conductors are shown attached to one face of the earplug in fig. 18-20, the conductors may alternatively be embedded within the earplug, as shown in fig. 21.

Referring to fig. 23, an exemplary embodiment of an active earbud 500 for two-way communication is shown. A substrate 505 is attached to the earplug 500, wherein the substrate 405 has conductors 510 and 520 present on both sides of the substrate to form an earplug with a combined microphone and speaker. Two pairs of electrodes (512, 514 and 522, 524 respectively) are placed at the ends of each conductor on either side of the substrate 505. An electrode 510 on one side of the substrate forms the output of the microphone and an electrode 520 on the other side of the substrate forms the input of the speaker. Note again that although the conductors are shown as a single trace for simplicity, their configuration may be more complex as described above. Furthermore, it should be understood that the substrate need not necessarily be attached to the outer surface of the earplug, but may also be embedded inside the earplug.

In one exemplary embodiment, the geometric relationship of the conductors for the microphone and speaker may be used to decouple their operation. During normal operation, current input to the speaker electrodes 522, 524 may cause vibration of the speaker conductor 520. Since the microphone conductor 510 is attached to the same substrate 505 as the speaker conductor 520, vibration of the speaker conductor 520 will displace the microphone conductor 510. This displacement will cause an undesirable voltage at the microphone electrodes 512, 514. To illustrate this more clearly, the microphone and speaker are highly coupled because the intended input to the speaker will cause an output at the microphone.

However, the coupling can be decoupled by using equations 1 and 2 above. Using equation 1, the forces exerted on the speaker conductor 520 and the microphone conductor 510 may be calculated for a generic time-varying speaker input. These forces can be converted into displacements using knowledge of the properties of the earplug material, such as elasticity and stiffness. This known displacement enables the velocity of the microphone conductor 510 to be determined, thereby estimating the expected output signal that may be present on the microphone electrode 510. The calculated output signal may then be removed from the microphone signal.

Referring to fig. 24, the microphone and speaker conductors are shown disposed on different substrates 540 and 540, where the two substrates are located at different locations on or within the earplug 500, including one or both substrates embedded within the earplug. In other exemplary embodiments, the speaker conductor or the microphone conductor may be formed directly on the proximal outer surface (the surface facing outward away from the head) of the earplug.

Referring to fig. 25, an exemplary embodiment of a cylindrical earplug 500 is shown that incorporates a plurality of turns of a coil conductor 550 wound around the exterior of the earplug 500. The voice-induced vibrations in the earbud 500 (through bone conduction) will have a rotational component that will cause the angle between the axis of the coil conductor and the static magnetic field to oscillate. This will cause a change in the magnetic flux circulating through the coil conductor 550, which will cause a voltage representative of speech to be present at the leads of the coil conductor 550. Thus, the earplug 500 including the coil conductor 550 may be used as a microphone. As in the microphone embodiments described above, this exemplary embodiment is also insensitive to ambient noise (e.g., noise generated by operation of the MRI scanner) due to the noise isolation provided by the distal insertable portion of the earbud 500, which closes the ear canal over at least a portion of its length. The coil conductors may be formed of materials including, but not limited to, insulated copper wire and other wires. Further, it should be understood that while the coil conductor 550 shown in fig. 25 is shown as being wrapped around the outer surface of the earplug, the coil conductor may alternatively be embedded within the earplug.

Referring to fig. 26, an exemplary embodiment of a rigid base plate 600 for attachment to a sound-deadening earplug and for use with a noise-isolating earplug is shown. The rigid substrate 600 includes a planar conductor 610, the planar conductor 610 functioning as a vibration speaker as described above when placed in a static magnetic field. The coil conductor 620 is located around the edge of the substrate 600 and may function as a microphone. When attached to or embedded in an earbud, the rigid substrate can be used for two-way communication, acting as both a vibrating microphone and a speaker in the static magnetic field of the MRI scanner. An advantage of this exemplary embodiment is that there is an inherent decoupling between the microphone and the loudspeaker. When used as a speaker, the planar conductor 610 will only produce a linear translation. When the coil conductor 620 is used as a microphone, it is only sensitive to vibrations having a rotational component, so the speaker and microphone will be inherently decoupled. It should also be understood that in another exemplary implementation, the designation and use of speaker and microphone may be reversed, such that the coil conductor 620 functions as a speaker and the planar conductor 610 functions as a microphone.

Fig. 27 shows another exemplary embodiment in which the coil conductors are implemented as planar coils disposed on the surface of the substrate 600. In the exemplary embodiment shown in fig. 27, the planar coil conductor 625 is disposed on the same plane as the speaker conductor 610. The operation of this configuration is the same as that of the previous embodiment, but has the advantage that it can be manufactured from a single-sided circuit board.

It should be noted that the position of the planar coil conductor is not limited to the peripheral area of the substrate as shown in fig. 27. The planar coil conductors may be placed in any suitable location. In one exemplary implementation, the planar coil conductor 625 may be located on the opposite side of the substrate 600 (i.e., opposite the surface of the substrate on which the speaker conductor 610 is located).

Fig. 28 shows an exemplary embodiment in which a cylindrical earplug 500 is provided with a substrate 600 attached thereto, wherein the substrate 600 includes a conductor 620 (having terminals 612 and 614) that serves as a vibration speaker. A vibration sensor 650 is also attached to the opposite side of the substrate 600, the vibration sensor 650 being capable of outputting a voltage proportional to the level of vibration experienced by the sensor 650. The vibration sensor 650 is capable of sensing the main static magnetic field B of the MRI scanner₀And may include, but is not limited to, a piezoelectric crystal, a piezoelectric bender, or an accelerometer. Such sensors are capable of sensing vibrations in a single discrete direction or in multiple orthogonal directions. The sensitivity of the sensor may also be omnidirectional.

In other exemplary implementations, the sensor 650 may be mounted on the same face as the vibrating speaker conductor 610. In the case where the sensor element is an accelerometer sensitive to acceleration in a single direction, the accelerometer may be mounted such that its direction of sensitivity is orthogonal to the vibrations produced by the vibration loudspeaker. In this way, the speaker and accelerometer can be decoupled such that the accelerometer is only sensitive to vibrations produced by the wearer through speech. In an exemplary embodiment where the accelerometer is sensitive to vibration in three orthogonal directions and is mounted such that the two sensitive directions are orthogonal to the vibration produced by the vibrating speaker, the measurements of both accelerometers will be decoupled from the vibrating speaker and can be combined to produce a signal representative of speech. Examples of methods for combining the measurements include, but are not limited to, linear addition or sum of squares addition.

In another exemplary embodiment, an accelerometer may be used as a vibration sensor that is sensitive to acceleration in three orthogonal directions. This configuration may provide additional flexibility in that the accelerometer may be mounted in any orientation on the substrate with the vibration speaker. Due to the arbitrary mounting of the accelerometer, it is expected that substrate vibrations generated by the operation of the vibration speaker will cause the accelerometer to signal in all three dimensions. The vector direction associated with the vibrating speaker can be identified by analyzing the measurement signals from the accelerometer in three directions, thereby removing the speaker signal. For example, a basis transform may be performed on the measured acceleration vector, and vector components associated with vector components of the vibrating speaker may be removed from the measurement results.

It should also be noted that the vibration sensor 650 described above need not be fixed to the substrate 600, but may be embedded in the earplug. Referring to fig. 29, an exemplary embodiment is shown in which an earbud 500 includes a substrate 600 and a vibration microphone sensor 650 embedded within the earbud 500, the substrate 600 having a vibration speaker located on an outer surface of the earbud 500.

While the previous embodiments disclose earplugs with attached or embedded conductors and sensors, other embodiments employing removable housings containing conductors or sensors may be provided. Referring to fig. 30A-30C, a noise isolating earplug 700 configured to occlude an ear canal when inserted into the ear canal is shown having a channel (e.g., hole, aperture) 710, the channel 710 being designed such that the earplug 700 fits securely to a housing 720 containing one or more acoustic transducers (such as, but not limited to, the acoustic transducers described above). The shell 720 includes a distal protrusion 730 that is received within the channel 710 such that vibrations generated by the acoustic transducer within the shell can be efficiently propagated to the earplugs and subsequently to the wearer's bone, and/or such that vibrations generated by speech are conducted through the earplugs and into the shell where they are detected by the acoustic transducer, i.e., the earplugs and the acoustic transducer are in acoustic conductive communication.

The vibration actuator in the foregoing example is not limited to the use of the lorentz mechanism. Referring to fig. 30, another type of vibration actuator may be placed in the housing so as not to utilize the static magnetic field of MRI. Such exemplary embodiments may therefore be used for non-MRI applications. Non-limiting examples of such devices include piezoelectric transducers, piezoelectric benders, and conventional magnetic speakers. As described above, the housing 720 should be mechanically coupled to the vibration actuator such that vibrations from the actuator are transmitted to the housing 720 and subsequently to the earplug 700.

Referring to fig. 31, a cross-section of an exemplary shell is shown with a protruding portion 730, the protruding portion 730 designed to mate with an earplug that completely occludes the ear canal. Inside the housing, a vibration actuator 760 is shown, wherein one side of the actuator is adhered and fixed to the inner surface of the housing 720. An acoustic conduit 740 (e.g., a post or other component) made of an acoustically conductive material connects the unsecured side of the vibrating element to the protrusion 730 to facilitate acoustic conduction of vibrational energy from the vibration actuator to the protrusion 730 engaged with the earplug.

In the foregoing examples, it should be understood that there are many possible configurations in which the earplug and the shell may be mated. It is desirable to have as large a mating surface as possible in order to achieve vibration conduction between the housing and the earplug. Referring to fig. 32, other possible embodiments include a housing 725 that surrounds and grips the protruding portion of the earplug.

Referring to fig. 33, an exemplary embodiment is shown with a vibrating element 760 embedded inside the earplug. A non-limiting example of such an actuator is a piezoelectric crystal. The actuator may be oriented such that a dominant vibration mode is generated in a direction perpendicular to the earplug and ear canal interface. Alternatively, the actuator may be oriented such that the vibration is generated and propagates in the axial direction of the earplug. Wires, such as insulated copper wires, are used to connect the vibration actuator to electronics 770 located outside the earplug, which electronics 770 will generate the signal to be actuated. An example of such electronics that cause the piezoelectric crystal to drive is a class G ceramic speaker driver, e.g., MAX9788, connected to a signal generator.

Referring to fig. 34, an earplug 700 is shown having an embedded actuator 760 and an embedded wireless module 780. This configuration does not require the use of any external wires. In this example, the wireless module may be a bluetooth receiver module having an audio protocol. The electronics also include a small battery, such as a lithium polymer battery, to power the electronics in the earbud.

Referring to fig. 35, an exemplary embodiment of a top support is shown. Two vibration actuators 800 are attached to a flexible headband 810 worn by the wearer. The vibration actuator 810 is in contact with an earplug worn by the wearer. The headband 810 applies pressure to the earplug. It should be noted that although the vibration actuators are shown exposed, they may also be enclosed in a cavity or "liner" that forms a seal over the ear, thereby providing further passive noise protection for the wearer.

To allow patients to benefit from noise reduction while allowing their heads to be scanned, the patient and communication device may be configured to fit within a head coil. Such an exemplary embodiment may be implemented with a head support similar to a conventional headphone, which is suspended from the top of the head as shown in fig. 35 and 36A. From a side view (fig. 36A), the headphone support is designed to prevent the vibrating element from sliding down off the ear when the patient is lying horizontally, and to provide sufficient compression on the head to provide contact between the vibrating element and the ear buds. As seen from the top of the patient's head in fig. 36B, the entire device is small enough to fit within a head coil comprised of head coil conductors 860 and head coil housing 870.

It should be appreciated that while many of the foregoing exemplary embodiments have been described with reference to applications involving communications in an MRI environment, many of the embodiments disclosed above may be applicable to a wide variety of other applications. For example, the active earbud embodiments described above that do not employ lorentz acoustic transducers may be used in applications other than magnetic resonance imaging communication systems.

Furthermore, the headrest-based exemplary embodiments described above may be used in a wide variety of medical applications beyond magnetic resonance imaging communications. For example, the headset may include fiducial markers for use in procedures involving image registration and/or surgical navigation, and/or be configured as a stereotactic frame with integrated speakers and/or microphones. In other exemplary implementations, the headrest need not be used in a horizontal configuration, but may be used in a reclined or upright configuration, such as a headrest in a vehicle or aircraft. The headrest may also be adapted as a helmet and may be used in applications in noisy environments, such as, but not limited to, military, factory, and heavy machinery operators.

The specific embodiments described above are shown by way of example, and it should be understood that various modifications and alternatives to those embodiments may be possible. It should be further understood that the claims are not intended to be limited to the particular forms disclosed, but rather to cover all modifications, equivalents, and alternatives falling within the spirit and scope of this disclosure.

Claims

1. An acoustic communication device for use during magnetic resonance imaging, the acoustic communication device comprising:

a headrest positionable within a magnetic resonance imaging scanner;

a vibration actuator supported by the headrest, wherein the vibration actuator is supported to: when the head of a subject is supported by the headrest, the vibration sound generated by the vibration actuator is coupled to an ear plug worn by the subject, and the vibration sound acoustically coupled to the ear plug is coupled to tissue surrounding the ear canal of the subject, thereby enabling the subject to hear the vibration through bone conduction; and

an audio circuit operatively connected to the vibration actuator for sending an audio signal to the vibration actuator.

2. The acoustic communication device of claim 1, wherein the vibration actuator is recessed within the headrest.

3. The acoustic communication device of claim 2, wherein the vibration actuator is configured to contact the ear plug when the head of the subject is supported by the headrest.

4. The acoustic communication device of any one of claims 1-3, further comprising one or more acoustic impedance matching layers disposed on the vibration actuator such that when the head of the subject is supported by the headrest, an outer surface of the one or more acoustic impedance matching layers contacts the earbud and vibration generated by the vibration actuator is acoustically coupled to the earbud through the one or more acoustic impedance matching layers.

5. The acoustic communication device of claim 1, wherein the vibration actuator is embedded within the headrest such that vibrations generated by the vibration actuator are conducted through an intermediate material before being acoustically coupled to the earbud by contact with the earbud.

6. The acoustic communication device of claim 5, wherein the intermediate material is part of a cushioning material of the headrest.

7. The acoustic communication device of claim 5, wherein the intermediate material is a sound conduit extending from the vibration actuator to the headrest surface such that when the head of the subject is supported by the headrest, vibrations acoustically conducted through the sound conduit are coupled to the ear insert by contact with the ear insert.

8. The acoustic communication device of claim 7, wherein the vibration actuator is located within a sound isolation region defined within the headrest, wherein the sound conduit extends into the sound isolation region such that when the head of the subject is supported by the headrest, vibrations generated by the vibration actuator are acoustically coupled to the ear plug through the sound conduit.

9. The acoustic communication device of claim 1, wherein the vibration actuator is supported by an outer surface of the headrest such that vibrations generated by the vibration actuator are conducted through an intermediate material within the headrest prior to being acoustically coupled to the earbud through contact with the earbud.

10. The acoustic communication device of any of claims 1-9, further comprising a bone conduction microphone configured to detect speech of the subject when the head of the subject is supported by the headrest.

11. The acoustic communication device of claim 10, wherein the headrest comprises a base cushioning region configured to contact and support a back side of the subject's head, wherein the bone conduction microphone is supported by the base cushioning region.

12. The acoustic communication device of claim 11, wherein the base buffer region is formed from memory foam.

13. The acoustic communication device of claim 11, wherein the headrest further comprises a support frame comprising:

a pair of lateral support members configured to contact sides of the subject's head when the subject's head is supported by the headrest, wherein one of the lateral support members supports the vibration actuator; and

a base support member supporting the base cushioning region.

14. The acoustic communication device of claim 13, wherein the lateral support member is pivotally mounted to the base support member, and wherein the lateral support member is rotationally biased to maintain contact between the headrest and the ear bud when the head of the subject is supported by the headrest.

15. The acoustic communication device of claim 14, wherein the lateral support member is translatable relative to the base buffer region in a direction parallel to a craniocaudal direction in order to align the lateral support member with the ear of the subject.

16. The acoustic communication device of claim 11, wherein the headrest further comprises lateral cushioning regions located on either side of the subject's head when the subject's head is supported by the headrest, wherein the vibration actuator is supported by one of the lateral cushioning regions, and wherein an acoustic isolation channel is provided between the lateral cushioning region supporting the vibration actuator and the base cushioning region for reducing the sensitivity of the bone conduction microphone to vibrations produced by the vibration actuator.

17. The acoustic communication device of claim 11, wherein the base cushioning region is formed of a first material, and wherein a lateral region of the headrest supporting the vibration actuator is formed of a second material, and wherein the first and second materials are selected to have different acoustic impedances for reducing sensitivity of the bone conduction microphone to vibrations generated by the vibration actuator.

18. The acoustic communication device of claim 11, wherein the headrest further comprises an intermediate region between the base buffer region of the headrest and a lateral region supporting the vibration actuator, wherein an acoustic impedance of the intermediate region is different from acoustic impedances of the base buffer region and the lateral region, thereby reducing sensitivity of the bone conduction microphone to vibrations generated by the vibration actuator.

19. The acoustic communication device of any of claims 1-10, wherein the headrest comprises lateral regions that are on either side of the subject's head when the subject's head is supported by the headrest, and wherein the headrest further comprises a support frame configured to bias the lateral regions against sides of the subject's head such that the headrest and the earplugs are in contact.

20. The acoustic communication device of any of claims 1-19, wherein the headrest further comprises a position adjustment mechanism to adjust a position of the vibration actuator to accommodate different head sizes.

21. The acoustic communication device of any of claims 1-20, wherein the headrest further comprises a magnetic resonance imaging head coil.

22. The acoustic communication device of any of claims 1 to 20, wherein the headrest has dimensions suitable for use within a magnetic resonance imaging head coil.

23. A bone conduction acoustic communication apparatus, comprising:

an elongate fluid conduit comprising a lumen;

means for introducing a fluid into the elongate fluid conduit such that the balloon is inserted into an ear canal of a subject in a non-inflated state, and subsequently introducing the fluid into the elongate fluid conduit such that the balloon is inflated with the fluid and closes the ear canal, thereby providing isolation from external acoustic noise; and

an acoustic transducer contacting the elongate fluid conduit at a location remote from the balloon such that when the balloon is inflated within the ear canal, the acoustic transducer is in acoustic conductive communication with tissue surrounding the ear canal via fluid residing in the elongate fluid conduit and the balloon, thereby facilitating acoustic communication from and/or to the direction of the subject via bone conduction;

wherein the acoustic transducer is connectable to an audio circuit for transmitting and/or receiving an audio signal.

24. The bone conduction acoustic communication device of claim 23, wherein the acoustic transducer is in contact with an outer surface of the elongate fluid conduit to effect acoustic coupling between the acoustic transducer and the fluid.

25. The bone conduction acoustic communication apparatus of claim 23, wherein the means for introducing a fluid comprises a syringe in fluid communication with the lumen, and wherein the acoustic energy transducer is supported by a piston of the syringe for generating or receiving longitudinal acoustic waves in the fluid.

26. An acoustic communication device for communicating in a noisy environment, the acoustic communication device comprising:

an acoustic transducer in contact with and supported by the noise isolating ear plug, wherein the acoustic transducer is supported such that upon insertion of the distal elongated portion into the ear canal, the acoustic transducer is in acoustic conductive communication with tissue surrounding the ear canal via the distal elongated portion of the noise isolating ear plug, thereby facilitating acoustic communication by bone conduction in a direction from and/or to the subject;

27. The acoustic communication device of claim 26, wherein the acoustic energy transducer is a lorentz transducer configured to detect or generate acoustic vibrations in the presence of a magnetic field.

28. The acoustic communication device of claim 27, wherein the lorentz transducer comprises a plurality of planar conductive paths.

29. The acoustic communication device of claim 28, wherein the plurality of planar conductive paths are defined on a substrate supported on or within the noise isolating earbud.

30. The acoustic communication device of claim 29, wherein the plurality of planar conductive paths is a first plurality of planar conductive paths defining a first lorentz transducer, the first plurality of planar conductive paths being disposed on a first side of the substrate, and wherein a second plurality of planar conductive paths is disposed on a second side of the substrate, the second plurality of planar conductive paths defining a second lorentz transducer such that one of the first and second lorentz transducers is operable as a speaker and the other of the first and second lorentz transducers is operable as a microphone.

31. The acoustic communication device of claim 29, wherein the substrate is supported on a surface of the noise isolating ear plug.

32. The acoustic communication device of claim 29, wherein the substrate is embedded within the noise isolating ear plug.

33. The acoustic communication device of claim 32, wherein the lorentz transducer is a first lorentz transducer, the acoustic communication device further comprising a second lorentz transducer supported on a surface of the noise isolating ear plug.

34. The acoustic communication device as claimed in claim 28 wherein the lorentz transducer is a first lorentz transducer, the acoustic communication device further comprising a second lorentz transducer provided as a coil supported on a surface of the distal elongated portion.

35. The acoustic communication device as claimed in claim 27, wherein the lorentz transducer is a first lorentz transducer, the acoustic communication device further comprising a second lorentz transducer provided as a planar coil.

36. The acoustic communication device of claim 26, wherein the acoustic energy transducer is an accelerometer.

37. The acoustic communication device of claim 26, wherein the acoustic energy transducer is a piezoelectric transducer.

38. The acoustic communication device of claim 26, wherein the distal elongate portion is formed of a viscoelastic polyurethane foam.

39. The acoustic communication device as claimed in any one of claims 26 to 38, wherein the acoustic energy transducer is disposed within a housing, and wherein the housing is connected to the noise isolating ear bud such that the acoustic energy transducer is acoustically coupled to the noise isolating ear bud without an intervening acoustic wave propagating in air.

40. An acoustic communication device for communicating in a noisy environment, the acoustic communication device comprising:

a headset configured to be worn on a head of a subject;

a vibration actuator supported by the headset, wherein the vibration actuator is supported such that when the headset is worn by the subject, vibration sound generated by the vibration actuator couples to an ear plug worn by the subject, and such that vibration sound acoustically coupled to the ear plug couples to tissue surrounding the ear canal of the subject, thereby enabling the subject to hear vibrations through bone conduction; and

41. The acoustic communication device of claim 40, wherein the headset comprises a pair of ear muffs.

42. The acoustic communication device of claim 40, wherein the headset is a helmet.

43. The acoustic communication device of any of claims 40-42, wherein the headset further comprises a bone conduction microphone configured to detect speech of the subject.

44. The acoustic communication device of claim 43, wherein the headset comprises a buffer region configured to contact a back side of the subject's head, wherein the bone conduction microphone is supported by the buffer region.

45. The acoustic communication device of any of claims 40-44, wherein the headset is sized for use within a magnetic resonance imaging head coil.